Revert "compfails also appeared after LLVM commit 214628 (tracker id 20540)"

This reverts commit 68577ae8a3e1b2e72f2889a318fbfc0dcb36e307.
Revert "add 12 runfails first appeared in LLVM 3.5 trunk on 26/07/14. these are now in trunk 3.6. erroneous commit 213898"

This reverts commit a9954dd8e7527a39f9cb4ea73bfee43de9afd259.
Revert "added 3.6 sse4-i16x8 compfails to fail_db"

This reverts commit e3c476112c57299a1d8d66dd9579967386fd7c3e.
Merge pull request #846 from ncos/knc_faildb

Reverted fail_db modifications after LLVM sse4 fix - see LLVM bug 20540.